07-09 18x9.5 GT500 wheels, what's the largest & widest tire that will work with these wheels? Originals were 255/45zr18. Should I keep it at that or can I go slightly larger all the way around? Any suggestions??

 

are all 4 the 9.5" wide?

or do you have the staggered setup with 9.5" and 10" out back?

the 9.5" wide would be fine running 275 or 285 width...the GT500 comes from the factory with 285 width out back on the 10" wides

 

I believe most tire specs state 285 max for a 9.5" width and 255 min, IIRC. I have a set of 07 GT500 takeoffs and run 275's all around but when I need tires it'll be 255's front and 285's rear. Those 275's up front tramline too much for my comfort.

 

07-09 GT500 come with 18x9.5 all 4 wheels.. Tires are 255 up front and 285 out back.. The widest recommended tire on that wheel is the 285.. Others have squeezed a nitto 305 rear onto them with very little bulge mainly due to nitto tends to run thinner than other tire brands

 

Thanks, I kinda figured that.
I was getting ready to order some FR500's & a friend turned me onto a set of new in the box GT500 wheels, original from Ford for $550. I couldn't turn that down. Now I just have to decide if I want the 285's out back or keep them the same size.

 

Staggered 255 front/285 rear will give your car some serious attitude.

 

Thanks, I kinda figured that.
I was getting ready to order some FR500's & a friend turned me onto a set of new in the box GT500 wheels, original from Ford for $550. I couldn't turn that down. Now I just have to decide if I want the 285's out back or keep them the same size.